Output problem with homemade 12v dc rectifier.

[Binary.Nation]

I'm trying to make a small 120v to 12v AC to DC converter and I have my retifier in place using the radio shack part 276-1152 along with the radio shack 12v 300mA transformer part # 273-1385.

After hooking them up and looking at the output on my oscilloscope to filter out the AC ripple, with out the filter my wave does not look right. Can someone tell me what's the issue? Below is a pic.

Rectifier
https://www.radioshack.com/product/...ype&numProdsPerPage=60&filterValue=Rectifiers
Transformer
https://www.radioshack.com/product/index.jsp?productId=2102494

View attachment 63123

 

[ericgibbs]

hi,
You should have the transformer and rectifier connected as shown in this image.

The scope should show a waveform as in the image [ sorry about the low quality rectified sine wave]

If you add a capacitor across the rectifier output say a 47uF at 25V working, the scope or a DC voltmeter should show approx 15V DC.

 

[ModemHead]

The scopes high input impedance does not allow enough current to flow for the diode to really switch on. You need at least a small load to see the textbook rectified sine waveform you expect. Even 100K resistor would be enough.

 

[Binary.Nation]

I had 4 LED's and a resistor to put a load on the circuit so that there wouldn't be any additional noise generated to affect the oscilloscope's reading. I found this pic which shows what the reading should be View attachment 63152 but if you look at mine where top hump from the lower negative half of the wave comes up to 12v, on mine the power goes to zero, but it looks like on wave I have, on both sides of the slope it looks like it bumps over then comes down. It sort of looks like to me the wave that was negative is out of phase.

 

[ericgibbs]

I had 4 LED's and a resistor to put a load on the circuit so that there wouldn't be any additional noise generated to affect the oscilloscope's reading. I found this pic which shows what the reading should be View attachment 63152 but if you look at mine where top hump from the lower negative half of the wave comes up to 12v, on mine the power goes to zero, but it looks like on wave I have, on both sides of the slope it looks like it bumps over then comes down. It sort of looks like to me the wave that was negative is out of phase.

hi,
Are you measuring with the scope the in way shown in my earlier image which shows how it should be connected.??